Semiconductor device and method for producing the same by dicing

ABSTRACT

A protective sheet is fixed to a jig, and regions of the protective sheet corresponding to regions where dicing-cut is to be performed are removed to form grooves. Then, a semiconductor wafer is bonded to the protective sheet at an opposite side of the jig, and the jig is detached from the protective sheet and the semiconductor wafer bonded together. After that, the semiconductor wafer is cut into semiconductor chips by dicing along the grooves of the protective sheet. Because the protective sheet is not cut by dicing, no scraps of the protective sheet is produced, thereby preventing contamination to the chips.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of JapanesePatent Applications No. 11-76566 filed on Mar. 19, 1999, and No.11-196345 filed on Jul. 9, 1999, the contents of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a method for producing a semiconductordevice by dicing a semiconductor wafer covered with a protective sheetalong scribe lines, a semiconductor device produced by the method, and awafer detachment apparatus usable for the method.

[0004] 2. Description of the Related Art

[0005] As disclosed in many documents such as JP-A-10-242253,JP-A-7-99172, U.S. Pat. Nos. 5,824,177, and 5,362,681, when asemiconductor wafer having plural movable portions is divided intoplural chips, a protective sheet is attached to the semiconductor waferto protect the movable portions. In this state, the semiconductor waferis diced into the chips together with the protective sheet at adicing-cut step.

[0006] In the conventional method described above, however, because theprotective sheet is diced together with the semiconductor wafer, scrapsof the protective sheet such as adhesive organic particles are producedby cutting and attached to the chips as contaminants. The scraps may beattached to electrodes formed on each chip to adversely affect theelectrodes in electrical and mechanical connection.

[0007] Further, in the conventional method, the protective sheet needsto be removed from the chips after the dicing-cut step is carried out.If the protective sheet is bonded to the semiconductor wafer firmly, theremoval of the protective sheet is difficult and may cause damages tothe chips by a stress. Therefore, the protective sheet is bonded to thesemiconductor wafer at relatively small adhesion. Because of this, theprotective sheet is easily separated from the semiconductor wafer duringthe dicing-cut step. As a result, the protective layer cannot protectthe movable portions sufficiently.

SUMMARY OF THE INVENTION

[0008] The present invention has been made in view of the aboveproblems. An object of the present invention is to prevent asemiconductor device from being contaminated by scraps of a protectivesheet produced when a semiconductor wafer covered with the protectivesheet is cut by dicing to form the semiconductor device. Another objectof the present invention is to provide a semiconductor device and amethod for producing the semiconductor device capable of preventingseparation of the protective sheet.

[0009] According to one aspect of the present invention, in a method forproducing a semiconductor device, after a protective sheet is fixed to ajig, a dicing-cut region of the protective sheet is removed. Then, asemiconductor wafer is bonded to the protective sheet, and the jig isdetached from the protective sheet and the semiconductor, whereby thesemiconductor wafer is exposed from the dicing-cut region of theprotective sheet. Then, the semiconductor wafer is cut by dicing alongthe dicing-cut region to form the semiconductor device.

[0010] In the method described above, because the dicing-cut region ofthe protective sheet is removed and the protective sheet is not cut bydicing, any scraps of the protective sheet are not produced by dicing.As a result, the semiconductor device is not contaminated by the scraps.Because a dicing blade does not contact the protective sheet, theseparation of the protective sheet is not caused by the dicing blade.

[0011] According to another aspect of the present invention, asemiconductor device has a semiconductor chip provided by cutting asemiconductor wafer by dicing, and a protective member disposed on thesemiconductor chip. A peripheral edge portion of the protective sheet isprovided at an inside of the peripheral edge portion of thesemiconductor chip. Because the peripheral edge portion of theprotective sheet is provided at the inside of the peripheral edgeportion of the semiconductor chip, a dicing blade does not contact theprotective member when cutting the semiconductor wafer. Therefore,generation of scraps and separation of the protective member can beprevented.

[0012] The inventors have further studied and examined the method forproducing the semiconductor device, and found out that when adhesionbetween the protective sheet and the jig was strong, the semiconductorwafer was easily broken when the protective sheet and the semiconductorwafer were detached from the jig.

[0013] To solve the problem described above, according to the presentinvention, the protective sheet and the semiconductor wafer are detachedfrom the jig by a pressure applied to the protective sheet from a sideof the jig. Accordingly, the semiconductor wafer can be detached withoutbeing damaged together with the protective sheet. Workability andthroughput for detaching the semiconductor wafer from the jig are alsoimproved.

[0014] Further, to solve the problem describe above, according toanother aspect of the present invention, a wafer detachment device isused for detaching the semiconductor wafer and the protective sheet fromthe jig. The wafer detachment device has the jig for fixedly holding theprotective sheet, and pressurizing means for applying a pressure to theprotective sheet. Accordingly, the protective sheet is detached from thejig by the pressure together with the semiconductor device readily.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other objects and features of the present invention will becomemore readily apparent from a better understanding of the preferredembodiments described below with reference to the following drawings, inwhich;

[0016]FIGS. 1A to 1E and 2A to 2C are cross-sectional views showing amethod for producing a semiconductor device in a stepwise manner in afirst preferred embodiment;

[0017]FIGS. 3A to 3E, 4A and 4B are cross-sectional views showing amethod for producing a semiconductor device in a stepwise manner in asecond preferred embodiment;

[0018]FIG. 5 is a cross-sectional view showing the semiconductor devicein the second embodiment;

[0019]FIG. 6 is a plan view schematically showing the semiconductordevice in the second embodiment;

[0020]FIG. 7A is a cross-sectional view schematically showing a modifiedsemiconductor device in the second embodiment;

[0021]FIG. 7B is a plan view schematically showing the modifiedsemiconductor device of FIG. 7A;

[0022]FIGS. 8A to 8F are cross-sectional views showing a method forproducing a semiconductor device in a stepwise manner in a thirdpreferred embodiment;

[0023]5FIG. 9 is a cross-sectional view showing a modified semiconductordevice in the third embodiment;

[0024]FIG. 10 is a cross-sectional view showing a case where a flatprotective member is used;

[0025]FIGS. 11A to 11E are cross-sectional views showing a method forproducing a semiconductor device in a stepwise manner in a fourthpreferred embodiment;

[0026]FIG. 12 is a cross-sectional view showing a modified semiconductordevice in the fourth embodiment;

[0027]FIGS. 13A to 13E are cross-sectional views showing a method forproducing a semiconductor device in a stepwise manner in a fifthpreferred embodiment;

[0028]FIGS. 14A to 14D, 15A to 15C, and 16A to 16C are cross-sectionalviews showing a method for producing a semiconductor device in astepwise manner in a sixth preferred embodiment; and

[0029]FIGS. 17A and 17B are cross-sectional views showing a method forproducing the semiconductor device using a modified reinforcement platein the sixth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the present invention are explained withreference to accompanying drawings. In the embodiments, a semiconductorwafer means a wafer before and after a dicing-cut step is carried outprovided that the wafer has a contour of its initial state.

[0031] (First Embodiment)

[0032] In a first preferred embodiment, a method for producing asemiconductor device according to the present invention is applied tovarious semiconductor devices including movable portions such as asurface micro-processed type acceleration sensor, a rotation anglesensor, and a reflecting digital micro-mirror projector (DMD). Themethod in the first embodiment is explained referring to FIGS. 1A to 1Eand 2A to 2C.

[0033] First, as shown in FIG. 1A, a protective sheet 1 is prepared. Theprotective sheet 1 is formed from an UV-setting adhesive sheet, a baseof which is made of, for example, polyolefine. The protective sheet 1has an adhesive surface 1 a for covering a semiconductor wafer 11, and asurface 1 b at an opposite side of the adhesive surface 1 a. Further, ajig 4 shown in FIG. 1B is disposed on a heater block (not shown). Thejig 4 has recesses 2 and holes 3 for vacuum absorption. The heater blockperforms the vacuum absorption in cooperation with the holes 3 of thejig 4.

[0034] Next, at a jig fixation step shown in FIG. 1C, the protectivesheet 1 is disposed on the jig 4 with the surface 1 b contacting the jig4 and the adhesive surface 1 a exposed upward. Then, the protectivesheet 1 is dented along the recesses 2 by vacuum absorption performedthrough the holes 3. Because the jig 4 is heated to a temperature in arange of 40 to 200° C., protective cap portions 5 are formed on theprotective sheet 1 with shapes corresponding to the recesses 2. Theprotective sheet 1 is fixed to the jig 4 by an attraction through theholes 3.

[0035] At a protective sheet region removal step shown in FIG. 1D, thejig 4 is detached from the heater block along with the protective sheet1 fixed to the jig 4. The jig 4 is then disposed on a base (not shown),which can absorb under vacuum as the heater block. Then, regions of theprotective sheet 1 where dicing-cut is to be performed at a dicing-cutstep described below are removed by cutting, thereby forming grooves 6at the removed regions (dicing-cut regions). As a result, the protectivesheet 1 is divided into regions having sizes approximately the same asthose of semiconductor chips to be formed. At this step, because theprotective sheet 1 is fixed to the jig 4 by vacuum absorption, theprotective sheet 1 is not loosed into pieces after the protective sheetregion removal step is carried out.

[0036] Next, at a wafer bonding step shown in FIG. 1E, the semiconductorwafer 11 having movable portions 10 and made of, for example, silicon isbonded to the protective sheet 1, by adhesives so that the movableportions 10 face the cap portions 5. The protective sheet 1 may be apressure sensitive adhesive sheet so that the semiconductor wafer 11 isbonded thereto. The positioning between the protective sheet 1 and thesemiconductor wafer 11 is performed by alignment keys formed on theprotective sheet 1 and the semiconductor wafer 11 or by a CCD camera. Aroller may be rolled on the semiconductor wafer 11 by heating thesemiconductor wafer 11 so that the semiconductor wafer 11 can be bondedto the protective sheet 1 without producing voids in the adhesives andlessening adhesion of the adhesives.

[0037] Then, a dicing sheet 12 is attached to the other surface of thesemiconductor wafer 11 at an opposite side of the movable portions 10.The dicing sheet 12 may be attached to the semiconductor wafer 11 beforethe semiconductor wafer 11 is bonded to the protective sheet 1. Byperforming the wafer bonding step described above, as shown in FIG. 1E,the semiconductor wafer 11 is attached to protective members (protectivecaps) 14 at one surface, and is attached to the dicing sheet 12 at theother surface. Each of the protective members 14 has a corresponding oneof the cap portions 5 and a size the same as that of each semiconductorchip, and is attached to the semiconductor wafer 11 while being fixed tothe jig 4. In FIG. 1E, although only one movable portion 10 is indicatedin each chip region, several movable portions 10 are provided in eachchip region usually.

[0038] Successively, at the dicing-cut step shown in FIG. 2A, after thejig 4 is detached from the protective sheet 1 (protective members 14),the semiconductor wafer 11 is fixed to a dicing base 13 by vacuumabsorption. In FIG. 2A, a detailed structure of the dicing base 13 isomitted. Then, the dicing-cut is performed along the grooves 6 where theprotective sheet 1 is removed, whereby the semiconductor wafer 11 isdivided into the semiconductor chips. At that time, the dicing sheet 12is not cut completely. The semiconductor chips are protected by therespective protective members 14.

[0039] In this dicing-cut step, the protective sheet 1 is not cut.Therefore, any scraps of the protective sheet 1 are not produced toremain on the semiconductor chips, thereby preventing contamination ofthe chips. In addition, because a dicing blade hardly contacts theprotective members 14 at the dicing-cut step, separation of theprotective members 14 is not caused by the dicing blade.

[0040] Because the protective sheet 1 needs not be attached to thesemiconductor wafer 11 so firmly, the removal of the protective members14 is easy. At a protective member removal step, as shown in FIG. 2B, aquartz glass jig 15 capable of performing vacuum absorption similarly tothe jig 4 is disposed on the protective members 14 covering thesemiconductor wafer 11. Then, UV irradiation is performed through thequartz glass jig 15 so that the adhesive is hardened to have lessenedadhesion, and the protective members 14 are removed by the vacuumabsorption. Accordingly, the state shown in FIG. 2C is provided.

[0041] The quartz glass jig 15 may have recesses as the jig 4 describedabove. Otherwise, the quartz glass jig 15 may have only holes for vacuumabsorption at positions corresponding to flat faces of the protectivemembers 14. Each semiconductor chip (semiconductor device) 100 formed byremoving the protective members 14 can be handled as an ordinal ICchips. Although the quartz glass jig 15 is used to remove the protectivemembers 14 in the present embodiment, other materials are usable as thejig 15 provided that the materials can transmit UV. The UV irradiationmay be performed using a mirror or an optical fibers provided that theentire wafer surface is irradiated with UV.

[0042] When the protective sheet 1 is made of a heat-contraction typeplastic film, the grooves 6 are widened due to heat contraction of theprotective sheet 1 after the protective sheet region removal step iscarried out. Therefore, the removed regions of the protective portions 1can be decreased. Also, because it is difficult for the dicing blade tocontact the protective sheet 1 at the dicing-cut step, the dicing-cutstep can be performed more readily. Preferably, the heat-contractiontype plastic film is selected from polyolefine family films such as apolyethylene film and a polypropylene film and films processed bydrawing such as a polyvinyl chloride film and a polyester film.

[0043] In the present embodiment, the protective sheet 1 is fixed to thejig 4 by vacuum absorption. Therefore, the protective sheet 1 can befixed to the jig 4 and be detached from the jig 4 readily without beingdamaged. Also, because the protective sheet 1 is not cut at thedicing-cut step, the life-time of the dicing blade is improved.

[0044] (Second Embodiment)

[0045] In a second preferred embodiment, the protective members(protective caps) 14 are formed similarly to the first embodiment.Differences from the first embodiment are that the semiconductor wafer11 has pad portions 21 for being electrically connected to externalcircuits by wire bonding (see FIG. 3E), and that the protective members14 are not removed and remain in products. Therefore, the protectivemembers 14 need to be partially removed at portions corresponding to thepad portions 21. The main differences from the first embodiment aredescribed in more detail below. It should be noted that the same partsas those in the first embodiment are assigned to the same referencenumerals in the second embodiment and other embodiments described below.

[0046]FIGS. 3A to 3E, 4A, and 4B schematically show the method forproducing the semiconductor device in the second embodiment in astepwise manner. The steps shown in FIGS. 3A, 3B and 3C are performed insubstantially the same manner as those shown in FIGS. 1A, 1B, and 1C. Ata protective sheet region removal step shown in FIG. 3D, regions of theprotective sheet 1 where the dicing-cut is to be performed and regionsof the protective sheet 1 corresponding to the pad portions 21 areremoved as in the step shown in FIG. 1D to form opening portions 23. Theregions corresponding to the pad portions 21 may be removed from theprotective sheet 1 in a sheet state by pressing or the like before theprotective sheet region removal step is carried out.

[0047] Next, at a wafer bonding step shown in FIG. 3E, the semiconductorwafer 11 is bonded to the protective sheet 1 so that the pad portions 21are exposed to the opening portions 23. Accordingly, both the padportions 21 and dicing-cut portions 22 are exposed to the respectiveopening portions 23. The other procedure at the wafer bonding step issubstantially the same as that in the first embodiment. In the presentembodiment, because the protective members 14 need not be removed, theprotective sheet 1 can be bonded firmly. This is preferable to preventthe separation of the protective sheet 1. It is not always necessary toexpose the pad portions 21 entirely. The pad portions 21 may bepartially exposed from respective windwos for wire bonding.

[0048] Next, as shown in FIG. 4A, the dicing-cut step is carried outsubstantially in the same manner as in the first embodiment, therebycutting the semiconductor wafer 11 into semiconductor chips (devices)200. In the present embodiment, as shown in FIG. 4B, each semiconductorchip 200 holds each protective member 14. After the dicing-cut step iscarried out, the semiconductor chips 200 are detached from the dicingsheet 12. Then, a wire-bonding step is performed to each semiconductorchip 200 so that wires are bonded to the pad portions 21 exposed fromthe opening portion 23 of the protective member 14. The pad portions 21are preferably cleaned before the wire-bonding step.

[0049]FIG. 5 shows a semiconductor device to which the wire-bonding stepis performed, as an example. A semiconductor acceleration sensor 31formed as one of the semiconductor chips 200 is disposed on a substrate30 (for example, ceramic substrate, printed circuit board, or leadframe) through adhesive (adhesive sheet) 32, silver paste or the like byhandling of a robot arm or the like. Next, a wire 33 made of gold,aluminum, or the like is bonded onto a pad portion 21 and a terminal 34disposed on the substrate 30. Thus, the wire-bonding step is carriedout.

[0050]FIG. 6 shows the acceleration sensor 31 (semiconductor chip 200)from a side of the protective member 14. As shown in FIG. 6, theprotective member 14 covers the acceleration sensor 31 except thedicing-cut portion 22 and the pad portions 21. The opening portion 23 isa portion not covered with the protective member 14. Further, FIGS. 7Aand 7B show a case where the pad portions 21 are partially exposed fromthe protective member 14, i.e., the opening portions 23 are formed topartially expose the pad portions 21.

[0051] Thus, according to the present embodiment, in addition to thesame effects as those in the first embodiment, the wire-bonding step canbe performed without removing the protective sheet 1 (protective member14) from the semiconductor chip 200. Because it is not necessary toremove the protective member 14 after the dicing-cut step, theprotective sheet 1 can be bonded to the wafer firmly. As a result, theseparation of the protective sheet 1 can be prevented more properly.

[0052] (Third Embodiment)

[0053]FIGS. 8A to 8F show a method for producing a semiconductor devicein a stepwise manner in a third preferred embodiment. In the first andsecond embodiments, the semiconductor wafer 11 is processed from onesurface thereof. To the contrary, in the present embodiment, thesemiconductor wafer 11 is processed from front and back surfacesthereof. That is, as shown in FIG. 8A, the semiconductor wafer 11 in thepresent embodiment has back surface processed portions 41 formed asopening portions by etching or the like performed from the back surface.The movable portions 10 are exposed from both front and back surfaces ofthe semiconductor wafer 11.

[0054] At a back side adhesive sheet bonding step, an adhesive sheet(back side protective sheet) 42 is bonded to the back surface of thesemiconductor wafer 11 to protect the back surface. Further, at thewafer bonding step, the protective sheet 1, which is processed as in thefirst embodiment to have the grooves 6, is bonded to the front surfaceof the semiconductor wafer 11 while being fixed to the jig 4. This stateis shown in FIG. 8B.

[0055] Then, as shown in FIG. 8C, the protective sheet 1 is detachedfrom the jig 4. After that, as shown in FIG. 8D, the semiconductor wafer11 is fixed to the dicing base (not shown in FIG. 8D) by vacuumabsorption through a dicing tape 12 a at the side of the adhesive film42. Then, the dicing-cut step is carried out as in the first embodiment.The dicing tape 12 a has the same function as that of the dicing sheet12, and is not cut completely.

[0056] Accordingly, the semiconductor wafer 11 is divided into chips. Asshown in FIG. 8E, each chip is protected by the protective member 14 atthe front surface side thereof, and by the adhesive film 42 at the backsurface side thereof. Then, as in the first embodiment, the protectivemember 14 is removed, thereby providing a semiconductor chip (device)300 shown in FIG. 8F. The semiconductor chip 300 can be handled as anordinal IC chip.

[0057] The present embodiment can be combined with the second embodimentin the formation of the protective member 14. FIG. 9 shows themodification. The protective member 14 protecting the front surface ofthe semiconductor chip 300 is formed to expose the pad portions 21 andthe dicing-cut portion 22 from an opening portion 23. Accordingly, thewire-bonding step can be performed to the semiconductor chip 300similarly to the acceleration sensor 31 shown in FIG. 5.

[0058] Thus, according to the present embodiment, the same effects asthose in the first and second embodiments can be provided. In addition,even when the movable portions 10 are exposed from both surfaces of thesemiconductor wafer 11, the movable portions 10 can be protectedappropriately.

[0059] At the dicing-cut step, two types of dicing blades may be used inaccordance with the characteristics of the adhesive sheet 42 to lengthenthe life-time of the dicing blades. Specifically, a first blade cuts thesemiconductor wafer 11 to some extent as indicated by arrow C1 in FIG.8D, and then, a second blade cuts the remaining semiconductor wafer 11,the adhesive film 42, and the dicing tape 12 a as indicated by arrow C2in FIG. 8D. The second blade is thicker than the first blade and made ofmaterial different from that of the first blade. Thus, two-step cuttingmay be carried out. When the thickness of the protective sheet 1(protective member 14) is increased to, for example, 50 μm, thesemiconductor wafer 11 can be cut from the back surface thereof.

[0060] The protective member 14 has the cap portion 5 not to contacteach movable portion 10 in the embodiments described above. The capportion 5 is formed by the jig 4 having the recesses 2. However, asshown in FIG. 10, an adhesive 52 may be disposed on a flat protectivemember 51 where the movable portions 10 of the semiconductor wafer 11 donot conflict. Accordingly, the protective member 51 can be preventedfrom contacting the movable portions 10 by the adhesive 52. Theprotective member 51 is formed by disposing the adhesive 52 on the flatprotective sheet 1, and by forming the grooves 6 or the opening portions23 in the protective sheet 1. In this case, the jig 4 can dispense withthe recesses 2, resulting in low cost.

[0061] (Fourth Embodiment)

[0062]FIGS. 11A to 11E show a method for producing a semiconductordevice in a stepwise manner in a fourth preferred embodiment. In thefourth embodiment, as shown in FIG. 11A, movable portions 61 are formedin the semiconductor wafer 11 at a depth in a range of approximately 0.5to 100 μm from a surface 60 of the wafer 11. In the present embodiment,specifically, a depth of a recess 62 defined by each movable portion 61and the surface 60 is set to approximately 3 μm. In this state, aprotective member (protective cap) 63 may be flat. Therefore, in thepresent embodiment, the jig fixation step, the protective sheet regionremoval step, the wafer bonding step, the back side protective sheetbonding step are performed as described above, while keeping theprotective film 1 flat without forming the cap portions 5, therebyforming the state shown in FIG. 11B.

[0063] Next, as shown in FIGS. 11C and 11D, the dicing-cut step and theprotective member removal step are carried out as in the thirdembodiment, thereby forming a semiconductor chip (semiconductor device)400 shown in FIG. 11E. The protective member 63 may be formed as in thesecond embodiment. FIG. 12 shows the semiconductor chip 400 formedaccordingly to have the protective member 63 exposing the pad portions21 therefrom. The semiconductor chip 400 shown in FIG. 12 can undergothe wire-bonding step while holding the protective member 63 as in thesecond embodiment.

[0064] Although the movable portions 10 are exposed from both front andback surfaces of the semiconductor wafer 11 in the present embodiment,the movable portions 10 may be exposed only from the front surface ofthe semiconductor wafer 11 as in the first and second embodimentsprovided that the movable portions 10 are formed in the wafer at a depthin a range of approximately 0.5 to 100 μm from the front surface of thewafer. Thus, according to the present embodiment, the same effects asthose in the first to third embodiments can be provided by applying theflat protective sheet (protective member 63) 1 to the semiconductorwafer 11 having the structure described above.

[0065] (Fifth Embodiment)

[0066] In a fifth preferred embodiment, a semiconductor chip 500 formedby dicing a semiconductor wafer 11 has bumps exposed therefrom for beingelectrically connected to external portions. FIGS. 13A to 13E show amethod for producing the semiconductor chip 500 in the fifth embodimentin a stepwise manner.

[0067] First, at a bump formation step shown in FIG. 13A, bumps 70 areformed on the front surface of the semiconductor wafer 11 to beelectrically connected to the pad portions 21. The bumps 70 are formedfrom, for example, eutectic solder or solder including In. Stud bumps(wire bumps) composed of gold balls, which are formed by wire bonding ofgold wires, may be adopted as the bumps 70.

[0068] At the jig fixation step, the protective sheet 1 is fixed to thejig 4. Then, at the protective sheet region removal step, the protectivesheet 1 is partially removed by excimer laser or the like to haverecesses 71 at regions corresponding to movable portions 61 of thesemiconductor wafer 11. The recesses 71 have the same function as thatof the cap portions 5 described above. If the movable portions 61 areprovided in the wafer 11 at a depth in a range of approximately 0.5 to100 μm from the wafer surface 60, it is not always necessary to form therecesses 71.

[0069] At the protective sheet region removal step, the grooves 6 arefurther formed in the protective sheet 1 fixed to the jig 4 at regions(scribe regions) where the dicing-cut is to be performed, therebydividing the protective sheet 1 into pieces each having a sizecorresponding to each semiconductor chip. At that time, regions of theprotective sheet 1 corresponding to the bumps 70 are also removed toform opening portions 72.

[0070] Next, the adhesive film 42 is bonded to the back surface of thesemiconductor wafer 11. At the wafer bonding step in the presentembodiment, protective members 73 formed by dividing the protectivesheet 1 are bonded to the front surface of the semiconductor wafer 11 toexpose the bumps 70 from the opening portions 72 while being fixed tothe jig 4. As a result, the sate shown in FIG. 13B is provided.

[0071] After the protective sheet 1 is detached from the jig 4, thedicing-cut step is carried out along the grooves 6 to divide thesemiconductor wafer 11 into chips (see FIG. 13C). Accordingly, asemiconductor chip 500 shown in FIG. 13D is obtained. The semiconductorchip 500 is covered with the protective member 73 having the openingportions 72, and the bumps 70 are exposed from the opening portions 72.

[0072] Further, a substrate 80 having a conductive layer 81 thereon isprepared. The substrate 80 is preferably a ceramic, glass,glass-ceramic, or silicon substrate, or a printed circuit board. Theconductive layer 81 is covered with an insulating layer 82 havingopening portions so that the conductive layer 81 is partially exposedfrom the opening portions.

[0073] Then, as shown in FIG. 13E, the semiconductor chip 500 isdisposed on the substrate 80 so that the bumps 70 contact the conductivelayer 80 exposed from the opening portions. The bumps 70 and theconductive layer 81 are electrically connected to each other by reflowor thermo compression bonding. Thus, a face down bonding, i.e., a flipchip mounting can be carried out.

[0074] When the bumps 70 are made of eutectic solder, the melting pointof the eutectic solder is approximately 180° C. In this case,preferably, the base constituting the protective member 73 is made ofheat resistant resin such as polyimide, and silicone adhesive is used asthe adhesive described above. The bumps 70 can be made of solderincluding In, a melting point of which is lower than that of eutecticsolder. The bumps 70 and the conductive layer 81 can be connected toeach other in a solid phase by thermal compression bonding at a lowertemperature. Otherwise, the bumps 70 may be connected by silver paste,which is generally used for fixation of chips onto a substrate.

[0075] Thus, according to the present embodiment, scraps of theprotective member 73 are hardly produced because the dicing-cut isperformed along the grooves 6. Because the protective member 73 needsnot be removed from the semiconductor chip 500, the protective member 73can be bonded to the semiconductor chip 500 firmly. As a result, theseparation of the protective member 73 is prevented. The semiconductorchip 500 can be electrically connected to the external substrate 80 bythe bumps 70 exposed from the opening portions 72 while holding theprotective member 73 thereon.

[0076] At the protective sheet region removal step in the presentembodiment, it is sufficient to form only the opening portions 72corresponding to the bumps 70. The grooves 6 may not be formed. In thiscase, the protective sheet 1 is cut along with the wafer 11 at thedicing-cut step. Even in this case, because the protective member needsnot be removed from the semiconductor chip and the protective sheet 1can be bonded to the semiconductor wafer 11 firmly, scraps andseparation of the protective sheet 1 can be prevented.

[0077] The protective sheet 1 in the present embodiment may have the capportions 5 as shown in FIG. 1, or be flat as shown in FIGS. 10 and 11.The movable portions may not be exposed from both surfaces of thesemiconductor wafer, but may be exposed from only one surface of thewafer as indicated in the first embodiment.

[0078] Incidentally, in the embodiments described above, as shown inFIGS. 5 to 7, 9, 12, and 13D, the semiconductor chip 200, 300, 400, or500 is covered with the protective members 14, 15, 63, or 73, and aperipheral edge portion S1 of each protective member is disposed at aninside of a peripheral edge portion S2 of each semiconductor chip. Thisis because the region of the protective sheet 1 where the dicing-cut ispreformed are removed at the protective sheet region removal step toform the grooves 6 or the opening portions 23. Because the peripheraledge portion S1 of the protective member is disposed at the inside ofthe peripheral edge portion S2 of the semiconductor chip, it isdifficult for the dicing blade to contact the protective member. As aresult, scraps of the protective sheet are hardly produced, and theseparation of the protective member does not occur.

[0079] If the peripheral edge portions of the protective member and thesemiconductor chip are provided at the same position, the protectivemember is liable to be separated from the chip when the side faces, theupper angular portions, the peripheral portion or the like of the chipare handled or pinched. As opposed to this, in the semiconductor chip200 to 500, because the peripheral edge portion S1 of the protectivemember is disposed at the inside of the peripheral edge portion S2 ofthe chip not to contact other members, the separation of the protectivemember hardly occurs during the handling.

[0080] (Sixth Embodiment)

[0081]FIGS. 14A to 14D, 15A to 15C, and 16A to 16C show a method forproducing a semiconductor device in a sixth preferred embodiment in astepwise manner. The sixth embodiment uses a semiconductor wafer 11,both surfaces of which are processed as in the third embodiment. Thesemiconductor device in the present embodiment is used for a capacitydetection type acceleration sensor. The semiconductor wafer 11 has backsurface processed portions 41 as opening portions so that sensingportions 10 a are exposed from front and back surfaces of the wafer 11.Each of the sensing portions 10 a is composed of a movable electrode anda fixed electrode.

[0082] As shown in FIG. 14A, an adhesive film (adhesive sheet) 42 isattached to the back surface of the semiconductor wafer 11. FIG. 14Bshows a jig 4 for forming protective cap portions 5. The jig 4 is a discand has several recesses 2 on one surface thereof for forming the capportions 5, and several holes (through holes) 3 communicating with therecesses 2 and opening at the other surface thereof for vacuumattraction.

[0083] Then, as shown in FIG. 14C, a vacuum chuck stage 600 is disposedin contact with the jig 4 at an opposite side of the recesses 2. Thevacuum chuck stage 600 has a pressure conduction hole 601 therein. Thepressure conduction hole 601 communicates with the respective holes 3 atan end thereof and with a vacuum pump (decompressing pump) at the otherend thereof. The jig 4 and the vacuum chuck stage 600 are sealed by anO-shaped ring 602. The vacuum attraction can be performed through thepressure conduction hole 601 in a direction indicated by an arrow P inFIG. 14C.

[0084] Next, as shown in FIG. 14D, the jig 4 and the vacuum chuck stage600 are heated to a temperature (for example, approximately 70° C.)capable of deforming the protective sheet 1. After that, at the jigfixation step, the protective sheet 1 is fixed to the surface of the jig4 while the vacuum pump is operated to perform the vacuum attraction.Accordingly, as described in the first embodiment, the protective sheet1 is deformed to have the cap portions 5 denting from a side of anadhesive surface 1 a toward a surface 1 b along the recesses 2 by anattraction force imparted from the holes 3. At that time, a dicing frame603 is disposed on an outer peripheral portion of the protective sheet 1to keep flatness of the sheet 1.

[0085] Next, at the wafer bonding step shown in FIG. 15A, thesemiconductor wafer 11 and the protective sheet 1 are positioned to eachother substantially in the same manner as in the first embodiment sothat the sensing portions 10 a face the respective cap portions 5. Then,the front surface of the semiconductor wafer 11 and the adhesive surfacela of the protective sheet 1 are bonded together, and then are cooleddown to a room temperature while keeping its state.

[0086] After cooled, at a reinforcement plate installation step shown inFIG. 15B, a reinforcement wafer 604 larger than that of thesemiconductor wafer 1 in diameter is disposed on the back surface of theadhesive film 42 as a reinforcement plate. The protective sheet 1 isbonded to the reinforcement wafer 604 at the outer peripheral portion ofthe adhesive surface 1 a thereof, whereby the protective sheet 1 and thesemiconductor wafer 11 are fixed to the reinforcement wafer 604. As aresult, the reinforcement wafer 604 is disposed to face the surface ofthe jig 4 where the recesses 2 are formed via the wafer 11 and the sheet1 interposed therebetween.

[0087] Next, the jig 4 is detached from the protective sheet 1. In thepresent embodiment, a pressure is applied to the protective sheet 1 viathe jig 4 in a direction indicated by an arrow P in FIG. 15B(pressurizing detachment step). Specifically, the connection of the endof the pressure conduction hole 601 is switched from the vacuum pump toa pressure supply apparatus not shown (for example, compressor). Theswitching of the connection can be performed by switching from a pipe(such as hose) system of the vacuum pump to a pipe system of thepressure supply apparatus by a switch bulb or the like.

[0088] The pressure supply apparatus supplies gas such as compressed airor nitrogen (N₂) into the holes 3 through the pressure conduction hole601, thereby performing the pressurization with a pressure ofapproximately 0.03 MPa. The cap portions 5 are not deformed by thedegree of pressure. In this pressurized state, the reinforcement wafer604 is detached from the jig 4 together with the semiconductor wafer 11and the protective sheet 1. At that time, because the semiconductorwafer 11 is supported by the reinforcement wafer 604 at the back surfaceside thereof, the semiconductor wafer 11 is not deformed (warped) anddamaged during the detachment. FIG. 15C shows the state after thedetachment is carried out.

[0089] Next, at a reinforcement plate removal step shown in FIG. 16A,the outer peripheral portion of the protective sheet 1 is removed bycutting, and accordingly the reinforcement wafer 60 is removed from thesemiconductor wafer 11. Because the reinforcement wafer 604 merelycontacts the adhesive film 42, those separation can be performedreadily. Next, as shown in FIG. 16B, a dicing sheet 12 is attached tothe back surface of the adhesive film 42, and the dicing-cut step iscarried out using a dicing blade 605. After that, as shown in FIG. 16C,the protective sheet 1 is removed, thereby dividing the semiconductorwafer 11 into chips. Incidentally, the jig 4, the reinforcement wafer(plate) 604, the pressure conduction hole 601, and the pressure supplyapparatus (pressurizing means) cooperatively serve as a wafer detachmentapparatus in the present embodiment.

[0090] According to the method in the present embodiment, after thesemiconductor wafer 11 is bonded to the adhesive surface la of theprotective sheet 1 closely fixed to the jig 4, the protective sheet 1 isdetached from the jig together with the semiconductor wafer 11. When theprotective sheet 1 is detached from the jig 4, a pressure is applied tothe protective sheet 1 through the jig 4 in a direction in which theprotective sheet 1 is detached.

[0091] Accordingly, the semiconductor wafer 11 bonded to the protectivesheet 1 can be readily detached under pressure without having anydamages. Thus, the wafer detachment can be performed with highworkability and high throughput according to the method of the presentembodiment. The reinforcement wafer 604 needs not be always adopted, butis effective to prevent the damages to the semiconductor wafer 11 moreproperly.

[0092] The jig 4 in the present embodiment has the recesses 2 and theholes 3 communicating with the recesses 2, and the protective sheet 1 isdeformed along the recesses 2 to have the cap portions 5. The capportions 5 protect the movable portions of the semiconductor wafer froma surface tension and a pressure of water during the dicing-cut step. Onthe other hand, the size of each semiconductor chip is decreased year byyear, so that the number of the chips formed by one wafer is increasedto, for example, 2000 to 3000.

[0093] In such a case, the large number of chips requires the samenumber of cap portions at least. Accordingly, the jig for forming thecap portions is required to have 2000 to 3000 recesses thereon. In thiscase, the protective sheet 1 is very difficult to be detached from thejig, because the protective sheet 1 is dented along the recesses.According to the present embodiment, however, the protective sheet canbe readily detached even in such a case, thereby solving the problemdescribed above.

[0094] The jig 4 may be flat only without having the recesses 2, andonly holes 3 may be formed in the jig 4. In this case, the cap portions5 are not formed to the protective sheet 1. This change does not affectthe effect of easily detaching the protective sheet 1 from the jig 4 bypressurization at all. Although both vacuum attraction andpressurization are performed through the holes 3, the jig 4 can haveother holes only for pressurization.

[0095] The method of the present embodiment described above does notinclude the protective sheet region removal step described in the firstto fifth embodiments. However, even when the protective sheet removalstep is carried out, the effect of the present embodiment can beexhibited as well. For example, the regions of the protective sheet 1corresponding to the scribe regions may be removed between the stepshown in FIG. 14D and the step shown in FIG. 15A. Even when theprotective sheet 1 is divided accordingly, because the protective sheet1 is fixed to the jig 4 by vacuum absorption, the divided sheet 1 is notloosed to be separated from one another.

[0096] The reinforcement plate of the wafer detachment apparatus is notlimited to the reinforcement wafer such as a silicon wafer, but may be apresser plate 606 shown in FIGS. 17A and 17B. In a modified embodimentshown in FIGS. 17A and 17B, the presser plate 606 is made of aluminum,and has a surface 607, and protruding portions 608 protruding from theouter peripheral portion of the surface 607 toward the jig 4. The areaof the surface 607 is larger than that of the semiconductor wafer 11.

[0097] At a reinforcement plate installation step using the presserplate 606, after the vacuum attraction is stopped, as shown in FIG. 17,the presser plate 606 and the jig 4 are fastened together by fixationscrews 609 inserted into screw holes of the presser plate 606 and thejig 4. Accordingly, the surface 607 of the plate 6 makes a specific gapwith the adhesive film 42 bonded to the semiconductor wafer 11. Thefront ends of the protruding portions 608 are supported by the surfaceof the jig 4 through the outer peripheral portion of the protectivesheet 1.

[0098] Next, at a pressurizing detachment step using the presser plate606, as described above, the pressure is applied to the protective sheet1 through the jig 4 in a direction in which the protective sheet 1 is tobe detached. Accordingly, the protective sheet 1 is slightly separatedfrom the jig 4 as shown in FIG. 17B. The back surface of thesemiconductor wafer 11 abuts the surface 607 of the presser plate 606through the adhesive film 42, and is supported by the surface 607.Consequently, the semiconductor wafer 11 can be prevented from beingdamaged more properly. After that, the fixation screws 609 areunfastened so that the presser plate 606 is detached from thesemiconductor wafer 11.

[0099] As described above, the reinforcement wafer 604 is fixed to thesemiconductor wafer 11 and the protective sheet 1 by the adhesivesurface 1 a of the protective sheet 1 adhering to the outer peripheralportion of the reinforcement wafer 604. Therefore, adhesives remain onthe reinforcement wafer 604 after usage. When the reinforcement wafer604 is reused as a reinforcement plate, it is necessary to prevent thesemiconductor wafer 11 from being contaminated by the adhesivesremaining on the reinforcement wafer 604. Because the positioningbetween the reinforcement wafer 604 and the semiconductor wafer 11 isnot easy, the reinforcement wafer 604 needs to be washed before beingreused to prevent the contamination to the semiconductor wafer 11.

[0100] On the other hand, the presser plate 606 described above has theprotruding portions 608 at the outer peripheral portion thereof, and theprotruding portions 608 support the semiconductor wafer 11. Thepositioning between the semiconductor wafer 11 and the presser plate 606can be easily carried out by utilizing the protruding portions 608 as areference. Because no adhesive adheres to the presser plate 606, thereis no possibility to contaminate the semiconductor wafer 11 by theadhesive. The reinforcement presser plate 606 needs not be washed whenreused, resulting in simplification of the manufacturing process.

[0101] While the present invention has been shown and described withreference to the foregoing preferred embodiments, it will be apparent tothose skilled in the art that changes in form and detail may be madetherein without departing from the scope of the invention as defined inthe appended claims.

[0102] For example, the semiconductor device in the present inventionmay be composed of a semiconductor chip encapsulated with resin. In theembodiments described above, the protective members have variousstructures such as a cap portion, a gap defined by adhesives, and arecess formed by excimer laser, thereby preventing contact with themovable portions of the semiconductor wafer. However, the structure ofthe protective member is not limited to those. In the embodimentsdescribed above, although several protective members are formed from oneprotective sheet fixed to the jig, the protective members may beindividually formed and fixedly arranged on the jig. The embodimentsdescribed above can be combined with one another selectively andappropriately. The present invention is not limited to a semiconductordevice having a movable portion, but can be applied to othersemiconductor devices and methods for producing the devices by cutting asemiconductor wafer covered with a protective sheet into chips bydicing.

What is claimed is:
 1. A method for producing a semiconductor device,comprising: fixing a protective sheet to a jig: removing a dicing-cutregion of the protective sheet fixed to the jig; bonding a semiconductorwafer to the protective sheet at an opposite side of the jig, theprotective sheet being fixed to the jig; detaching the protective sheetand the semiconductor wafer from the jig whereby the semiconductor waferis exposed from the dicing-cut region where the protective sheet isremoved; and cutting the semiconductor wafer along the dicing-cut regionby dicing.
 2. The method of claim 1, further comprising: forming a padportion on a surface of the semiconductor wafer to be bonded to theprotective sheet; removing a pad region of the protective sheet togetherwith the dicing-cut region to form an opening portion for exposing thepad portion therefrom when the semiconductor wafer and the protectivesheet are bonded together; and bonding a wire to the pad portion exposedfrom the opening portion of the protective sheet after cutting thesemiconductor wafer along the dicing-cut region by dicing.
 3. The methodof claim 1, wherein removing the dicing-cut region of the protectivesheet is carried out by cutting the dicing-cut region to form a groove.4. The method of claim 1, wherein the protective sheet is made of aheat-contraction type plastic film.
 5. The method of claim 1, furthercomprising attaching a back side sheet to the semiconductor wafer at anopposite side of the protective sheet before cutting the semiconductorwafer.
 6. The method of claim 1, wherein the protective sheet is fixedto the jig by vacuum absorption.
 7. The method of claim 1, whereindetaching the protective sheet and the semiconductor wafer from the jigincludes applying a pressure to the protective sheet from a side of thejig.
 8. A method for producing a semiconductor device, comprising:preparing a semiconductor wafer and a protective sheet; forming a bumpon a main surface of the semiconductor wafer; forming an opening portionin the protective sheet; bonding the main surface of the semiconductorwafer to the protective sheet so that the bump is exposed from theopening portion; and cutting the semiconductor wafer by dicing to form asemiconductor device covered with the protective sheet and having thebump exposed from the opening portion.
 9. The method of claim 8, furthercomprising: preparing a substrate having a conductive portion thereon;disposing the semiconductor device on the substrate with the bumpcontacting the conductive portion; and electrically connecting the bumpto the conductive portion.
 10. The method of claim 8, furthercomprising: fixing the protective sheet to a jig by vacuum absorptionbefore forming the opening portion in the protective sheet; anddetaching the jig from the protective sheet after bonding thesemiconductor wafer to the protective sheet.
 11. The method of claim 10,wherein detaching the jig from the protective sheet includes applying apressure to the protective sheet through a hole defined in the jig. 12.A method for producing a semiconductor device, comprising: fixing aprotective sheet to a jig; bonding a semiconductor wafer to theprotective sheet at an opposite side of the jig; detaching theprotective sheet and the semiconductor wafer from the jig by a pressureapplied to the protective sheet from a side of the jig.
 13. The methodof claim 12, wherein the pressure is applied to the protective sheetthrough a hole defined in the jig.
 14. A semiconductor devicecomprising: a semiconductor chip provided by cutting a semiconductorwafer by dicing: and a protective member disposed on the semiconductorchip, the protective member being for protecting the semiconductor chipwhen the semiconductor wafer is cut by dicing, wherein a peripheral edgeportion of the protective member is provided at an inside of aperipheral edge portion of the semiconductor chip.
 15. A semiconductordevice comprising: a semiconductor chip provided by cutting asemiconductor wafer by dicing; a bump disposed on a surface of thesemiconductor chip; a protective member disposed on the surface of thesemiconductor chip and having an opening portion from which the bump isexposed, the protective member being for protecting the semiconductorchip when the semiconductor wafer is cut by dicing.
 16. A waferdetachment apparatus comprising; a jig for fixedly holding a protectivesheet thereon, the protective sheet being for protecting a semiconductorwafer by covering the semiconductor wafer; and pressurizing means forapplying a pressure to the protective sheet so that the protective sheetis detached from the jig by the pressure together with the semiconductorwafer which is bonded to the protective sheet at an opposite side of thejig.
 17. The wafer detachment apparatus of claim 16, wherein thepressurizing means applies the pressure to the protective sheet througha through hole defined in the jig.
 18. The wafer detachment apparatus ofclaim 16, wherein: the jig has a plurality of recesses on a surfacethereof for fixedly holding the protective sheet, and a plurality ofholes respectively, communicating with the plurality of recesses; andthe jig deforms the protective sheet fixed thereon along the pluralityof recesses by absorption performed through the plurality of holes. 19.The wafer detachment apparatus of claim 16, further comprising areinforcement plate for supporting the semiconductor wafer at anopposite side of the protective sheet when the protective sheet and thesemiconductor wafer are detached from the jig.
 20. The wafer detachmentapparatus of claim 19, wherein the reinforcement plate has a supportsurface for supporting the semiconductor wafer, and a protruding portionprotruding toward the jig from an outer peripheral portion of thesupport surface.